The present invention relates an exposure device including light emitting elements, an LED head including LEDs, an image forming apparatus including the exposure device, and an image reading apparatus.
An exposure device includes a plurality of LED (Light Emitting Diode) arrays each of which includes a plurality of LEDs linearly arranged in a scanning direction. The LED arrays are arranged in at least two rows in a staggered manner. An interval in the scanning direction between the endmost LEDs of the adjacent LED arrays of the different rows is set to be the same as an interval between the adjacent LEDs of the same LED array. Such an exposure device is disclosed in, for example, Japanese Patent Application Publication No. 2004-209992 (see Page 4, FIG. 2).
However, in the general exposure device, the LED arrays may expand or contract due to changes in temperature and humidity. Therefore, it is difficult to manage the interval in the scanning direction between the endmost LEDs of the adjacent LED arrays of the different rows within an allowable range. Therefore, exposure accuracy or image reading accuracy may be lowered. As a result, printing quality or reading quality may be lowered.